The invention relates to a switch fitting.
The sealing of switch shafts with respect to a fitting housing is critical since leakages may occur, in particular on rotation operation of the switch shafts by way of a one-sided lever. Due to this there is exerted onto the switch shaft a tilting moment by way of which on the one hand the seal is pressed together and on the other hand permits the formation of gaps.
From DE-U-78 15 061 there is disclosed a switchable fitting whose switch shaft impinged by pressure, for securing in the fitting housing, has two radial collars axially distanced from one another, with spherical sealing surfaces which in each case are supported on graduations of a two-stepped switch shaft bore via sealing rings with spherical seating surfaces. The switch shaft is pressed and pulled in its sealing seating by the housing inner pressure as well as also by the result of the pretensioning of disk springs, wherein the disk springs on the one side are supported on the outer side of the fitting housing, and on the other side on a counter bearing rigid with the switch shaft. This design has the disadvantage that the inner pressure of the switch fitting as well as a wear of the seals act against the spring pretensioning. The switch shaft can only be tilted with a considerable gap formation between collars and sealing surfaces, since the spherical sealing seatings have radius middle points which are considerably axially displaced.
From DE 21 40 975 there is known a switch shaft seal for switch fittings whose switch shaft comprises an annular collar with plane annular surfaces for the bearing of two seal arrangements in each case of two wedge-like sealing rings engaging into one another. Furthermore DE 26 58 256 discloses a sealing device for the spindle of a fitting in which a sealing ring with a ball-shaped sealing seat is pressed against the spherical sealing surface of a radial collar of the spindle by way of a disk spring. The sealing surface is arranged on the inner-lying side of the collar so that the disk springs are supported on one inner step of the spindle bore and have contact with a medium flowing through. The collar is supported on the outside on a counter bearing rigid with the housing via a plane annular surface so that a tilt movability of the spindle is not effected.
Finally a switch fitting it is known from DE 41 04 003 in which a single collar on the switch shaft forms oppositely lying sealing surfaces which are spherically shaped and which cooperate with correspondingly shaped sealing rings on oppositely lying sides, wherein the spring acts on a pressure ring which bears against the facing sealing ring, in order to press this sealing ring against the collar. With this switch fitting the sealing rings and the collar of the switch shaft are pressed together without play. The compression spring ensures the compensation of manufacturing tolerances, extension variations and wear, so that in the normal case a subsequent setting of the seal is required. By way of the spherical sealing and seating surfaces on both sides of the same collar there is created a gap-free sealing bearing, and deposits by way of connection to the mediums between the switch shaft and the switch shaft bore are avoided. The known design requires high torques for its operation which is also the case for the switch shaft mountings described further above.